A burglar alarm is not a substitute for good security locks on doors and windows, but it is excellent in conjunction with them — the exterior bell box acting as a visual deterrent and the alarm system itself detecting an intruder before he has time to steal property or create havoc inside the home. It is important that you arm the system at night and whenever the dwelling is empty, and that it is reliable. A number of false alarms will prevent police and neighbours taking notice of a genuine alarm call, and may even dissuade you, the householder, from using the alarm regularly.
The usual DIY burglar-alarm kits are wired-circuit alarm systems consisting of a control unit, an external self-actuating alarm bell or siren, specialised detectors and sensors, which in most kits comprise magnetic contacts for doors and windows and pressure mats, and one or more panic switches together with the necessary cable, clips and connectors to form an electrical circuit. A good kit will contain both closed circuit devices, such as magnetic contacts, in wi. It the alarm sounds if a continuous current broken, and open circuit devices, such as pressure mats, in which the alarm sounds if a circuit is completed. Open circuit devices should not be used alone because if the connecting wires are cut the alarm will not be triggered off.
Another type of alarm is the ultrasonic unit which detects an intruder within a defined area. These self-contained units can resemble hi-fi speakers and simply plug into the mains supply and have back-up batteries. They vary in sophistication and may have a walk-test facility, which lets you set the pattern of the area to be guarded, remote alarm, and other features.
A passive infrared detector triggers the alarm if any change in the heat of the room occurs, such as the heat from the body of an intruder. Careful positioning of the detector is necessary to prevent false alarms.
Both ultrasonic and infrared units may be incorporated into a conventional alarm system and used to protect high-risk areas.
Installing a system
Start by familiarising yourself with the various items in the kit. With short lengths of wire, connect up the control unit and exterior bell or siren to ensure that all the pieces are working correctly before they are finally installed when fault-finding is more difficult. Smother the alarm with a cushion during these tests.
The next stage is to decide where the various devices will be installed. A typical domestic layout is shown in the diagram. This illustrates how the likely entry points can be protected and how carefully placed pressure mats will quickly detect the movement of an intruder inside the house. It is not a good idea to have pressure mats between the control unit and front door as this would deny the keyholder free entry and exit, unless the control box incorporated a time-delay facility or there was a key-switch outside the door.
The actual installation of the various devices is quite easy if you follow the manufacturer’s instructions. Usually, it is just a simple wiring job using 2-core cable supplied in the kit.
Lighting can help security in two ways — it can make the house seem to be occupied when it is not, and it can illuminate dark areas outside the house to make it harder for an intruder to lurk unseen.
In the evenings, a dark house is almost certainly unoccupied so it usually pays to leave a light on somewhere, although not solely in a hallway, and not in a ground-floor room with the curtains drawn back so that anyone looking through the window can see that the room is unoccupied.
If you are going away for a long period you should not leave lights burning by day (another sign that a house is unoccupied) and by night. It is best to fit some sort of time-switch so that the lights come on automatically in the evening and go off again at bedtime.
The simplest time-switch is the plug-in type which fits into an ordinary socket outlet (power point). Time-switches can usually be set to allow up to two on/off switchings in a 24-hour period, although there are more expensive models allowing a
greater number of switchings. They can only be used for plugged-in lights, such as table lamps or standard lamps, and not to switch the central room-light on and off. However, used in a bedroom or living-room, they can give the effect that the house is occupied, although anyone studying the house over a period of days may notice that the lights go on and off at identical times each day.
To avoid this there are random switching devices available and one of the best of these is a unit which replaces the wall switch in a room and can therefore control the main light. The switch can be used as a conventional light switch, but it is also programmable and will either ‘learn’ and repeat automatically the way the light is normally used over a period of time, or it can be programmed to switch the light on and off a number of times in any 24-hour period. These times are varied up to half an hour each day to give random switching.
It is a good idea to fit a wall-mounted lamp above both the front and back doors. Small, powerful wall-mounted floodlights are available for illuminating patios, driveways and other parts of the garden. If lights are installed in the garden these should be either 12 volt garden lights working from a transformer which is kept indoors, or if mains-operated, a professionally installed system connected by means of armoured outdoor cable. Low voltage cable should be buried in a trench and covered with tiles to prevent accidental damage.
All the measures described so far have been aimed, in the first instance, at protecting property. Unfortunately, however, there is an ever-increasing need to take account of personal security. It is a sad fact of life that even at home you cannot be certain that you will not be subjected to a personal attack from an intruder, and the barge-in type of theft is on the increase, particularly in flats.
Two very easy ways to increase your security at home are to fit a door viewer and a door security chain.
A door viewer contains a special lens which gives a very wide angle of view when mounted at eye height in a front door, allowing you to identify callers before opening the door. It is supplied in two parts and fitting is simply a matter of drilling a hole through the door and screwing the two parts of the viewer together after inserting one part from the front of the door and the other section from the back.
These should be strong, and fixed with large, long screws to minimise the risk of the chain fittings being wrenched from the door. The chain anchor should be screwed to the door-frame and the metal channel in which the other end of the chain can slide is fixed to the door. Some door chains have the chain attached to a key-operated plunger which allows the chain to be secured when you leave the property as well as in the conventional manner but it should never be used in place of a security lock. Get into the habit of always securing the door chain when you are at home.
A further aid to personal security is provided by many burglar alarms which incorporate panic buttons or personal-attack switches into the system. The panic buttons are usually mounted near the front door and beside the bed, and pressing one of these buttons in an emergency sounds the alarm regardless of whether the main system is switched on or off.
Another electronic aid to security is the doorphone. This can simply be a two-way intercom system which will enable you to identify a caller, as an alternative to a door viewer, or it can be a sophisticated system, which may include a television door-viewer, and incorporate an electric door-release mechanism which can be especially useful in flats to minimise trips up and down stairs.
As a deterrent to attacks outdoors there are several, small anti-personnel whistles and sirens working off a canister of compressed air or batteries which emit a painful noise to drive-off attackers and attract the attention of passers-by.
Cooker which is turned on. If the fat gets too hot it can ignite spontaneously. Be careful when adding wet chips to hot fat as the fat can splash and ignite. Do not leave tea-towels and clothes to dry over a cooker. Avoid curtains in a kitchen; if the window is left open there is a danger that the curtain will blow into a gas burner. Window blinds are safer in this respect. Make sure that electrical appliances are frequently checked for frayed flexes, broken plugs and loose connections. Never overload socket outlets by using multiple adapters.
In other areas of the house, make sure that portable electric and gas fires are not left where they could ignite furniture and curtains, or where someone could trip over them. Make sure that open fires are guarded. Chimneys for open fires should be swept at least once a year. Never move or fill oil-heaters when they are alight. Make sure that the heater is kept out of draughts and if possible fix it to the floor. Never use electric blankets when creased or folded and never leave them on all night unless they are the overblanket type. Unplug television sets before going to bed, check that fires are on their night-time setting; check ashtrays for smouldering cigarette ends, and close internal doors to inhibit the spread of fire.
Smoke detectors and extinguishers
It is an excellent idea to fit a smoke detector to give warning of a fire at an early stage. Most domestic smoke-detectors are battery-operated ionisation units which detect invisible products of combustion at an early
stage and then sound an alarm. A good unit should sound a warning when the battery needs to be replaced and there should be a test button to check that the unit is working properly.
A range of fire extinguishers is available. Dry powder and vaporising liquid types are the most versatile and can be used on any type of fire.
Finally, and very important, ensure that everyone who needs to know — members of the family, guests and baby-sitters, for example — is aware of the position of essential keys and how to use them, in the event of an emergency.